Island



|. W. KNIGHT.

SAFETY DEVICE FOR GAS BURNERS.

APPucATloN FILED 1AN.21. |919.

` Patented Nov. a, 1919.

' cham'ber.

IEA w. KNIGHT, or. PROVIDENCE, RHODE ISLAND, AssIeNon 'ro GENERAL FIRE ExTmeUIsHEa COMPANY, or raovIDENCE, HHoDE IsLAnnn CORPORATION OF4 NEW YORK.

smettila(l DEVICE ronces-Dummies.

Application led January 27 1919. Serial No. 273,301. I

To all whom z'may concern: Y Be it known that l, IRA W. KNIGHT, a citizen of the United States, residing at Providence, in the county of Providence and.y

heating or other purposes, and having a mixing chamber in which gas and a limited amount of air, known as primary air, are mixed, whence the mixture escapes through ports into the atmosphere and, with the addition of secondary air, burns with a blue flame. Burners of this type, which are comanon in vvarious forms, and are applied to various uses, are generally subject to the danger that the flame may pass back through the burner ports into the mixing Various devices have beenproposed'to prevent such a flash-back; but none so far as I am aware has been devised prior to the present invention to protect the apparatus from danger in case a Hash-back actually occurs. The marked utility of burners arranged for heating under thermostati-c control has led to the designing of apparatus in various forms in which the gas isautomatically turned on and ignited when the temperature in the medium that is to be controlled falls to a predetermined level. In such cases, as the apparatus works regardless of human attendance, the occurrence of a flash-'back may not 'be known for a long time. It is a purpose of the present invention to prevent such danger by providing for automatic shut-.off of the gas.

The invention is illustrated as it may be applied to a burner having an electricallycontrolled gas valve, held open by the electric current. It operates by breaking the electric current whenever the interior of the burner becomes unduly heated,.as happens in case of a flash-back with consequent combustion occurring within the mixing chamber. This breaking of the electric current is occasioned by the separation-of two parts of the conductor carrying the electric cur rent, consequent upon the fusing of a joint by which they are normally held together.

Although illustrated in connection with an electrically-controlled valve, the source of power by which the circuit is broken is mechanical,l being in the vcase illustrated the expansion. of 'a spring, yand so it may be understood that the invention is not limited to use with valves controlled by any electric currentpbut that the mechanical power released Iby the fusing which follows the occurrence of a flash-back can ,operate any other Specification of Letters Patent. l Patented NOV. 1, 1919.

suitable sort of 'device for shutting olf the as. 1n the larrangement of the fusible part in a removable plug in theburner, preferably in a conveniently accessible part of the mixing chamben. When -a flash-back has occurred and thel apparatus of the invention `has operated, the gas will be left shut off and in safe condition; but operating conditions may be restored vby an attendant simply substituting a new plug.

In the accompanying drawings:

Figure 1 is a xside, elevation in medi-al section showing an embodiment of the invention as it may be attached to and used in connection with an automatically controlled gas burner;

Fig. '2 is an end elevation of a part of the same;

Fig. 8 is a sectional view of the preferred form of plug; and

Fig. 4 is a similar view of a different form of plug. t

Referring to the drawings, 10 indicates a gas supp-ly pipe which leads into a casing 11 containing a valve 12 and connected with a burner 13 having a port 14 for entrance of the gas, which becomes mixed in the chaniber 15 with .primary air that enters the same through a shutter-regulable port 16. The burner 13 is represented as if arranged in connection with aradiator or other heating appliance 17, a fragment of Ywhich 1s shown. The appliance 17 may be vunderstood to extend toward the right in Fig. l with the burner in it or under it and where are ports (not shown) for the escape of the mixture, outside of which ports is the normal position of the flame. `When la flash-back occurs, combustion follows in the interior 15 of the burner 13, especially in the part shown in the drawing where the air entering through 16 rst mingles with the gas coming through 14. The construction thus illustrated is no part of the invention but typifies varlous forms of construction to which the invention may be applied.

One feature of the invention consists therefrom A principal feature of the invention is through the conductor 31, binding post 33,

found in a screw or otherwise removable plug 20 whose general arrangementwith resp'ect tothe burner and mixing chamber is illustrated in Fig-1, and whose details of construction are seen in Fig. v3. As thus illustrated, the plug fills an opening inthe mixing chambers wall, made to receive it and so located that the inner end of the plug is exposed to the temperature conditions in the mixing chamber, preferably close to the'place where the primary air and gas rst come together. As illustrated, theA plug consists of a tubular piece of metal 20- whose central passage 21 is closed by a disk 22 held rigidly and permanently in place by any suitable means, as by a .turned-over lip or bead 23, which holds the disk down on a seat 24. k1Within the hollow 21 is insulating material 25, 26, of suitable size and shape to receive and to insulate from the metal 20, 22, a coiled spring 27 while permitting a central core28 to pass through and make end contact with the disk 22. Preferably .the insulation is'in two pieces, one a sort of washer 26, resting against the disk 22 and having a central hole large enough for the post 28 to pass through loosely, and the other a cylindrical shell 25 extending from the washer through thevpl-ug to the outer face thereof and incasin the'. spring 27. rIhe latter bears against the washer 26 and is normally under compression, pressing against the outside head 29 of post 28, so that the outward pressure of the sprmg tends constantly to push the post 28 out of the plug and away from the disk 22. The post 28 is, however, normally held 1n the position illustrated by its inner end, being soldered tothe said disk 22, b. a layer of solder indicated by the thick inev 30, of such a composition as will melt at a predetermined temperature well above any temperature reached by it when the plug is set in place and the burner is operating normally, but below the temperature which the region of the plug attains'when a flash-back has occurred and the flame is burning in the mlxing chamber. The spring 27, being under compression, thrusts the post 28 out of the plug when the solder at 30 is thus melted. The tute a portion of an electrical circuit comprising the flexible conductor 31- having ordlnary insulation 32 and secured by any suitable means to the head 29; said central post ,28; the fusible solder 30; the disk 22; and the metal 20 of the plug. The head 29 1s insulated from the plug metal 2O except through the course mentloned. When installed for use, the circuitis grounded through this metal 20 and the metal 13 of the burner tothe battery, generator, or other source of current (not shown). In the other d1rect1on, the circuit comes to the plug parts illustrated'in Fig. 3 constielectro-magnet 34, binding p ost '35, yand the conductor indicated in dotted lines, from .the said battery, generato-r or other source. The magnet 34 has an armature 36 which' controls the gas valve 12. The latter consists of a ball or other device adapted to fall-upon its seat 12 by gravity, thus shutting off the gas, and to be lifted therefrom when a current passes through the magnet 34 to lthe armature 36 to which it is attached.

In a thermostatically controlled heater, the well known loperation of the thermostat (not shown in the. present drawings) is to make an electrical" connectionsuch that a current passes through the magnet, thus opening the valve l2 and letting gas into orl apparatus which controls the thermostat as to cause a normal shut-'off of the gas.

The operation of the present invention is,

however, very prompt to shuton' the gas, because the parts of the plug 20 are 1ncluded in the circuit which controls the mag net 34.- Upon abnormal rise of tempera'- ture in the mixing chamber the melting of the solder 3() permits the spring 27 to throw the post 28v out 'of the plug, or at least to throw it far enough to separate it from the disk 22, thus breaking the circuit and terminating the lifting e'ect of the magnet 3l on the armature and valve, 36, 12. Ordinarily, the place for the plug 20 should be so positioned that the' post will be thrown clear of the other apparatus when ejected;

kand the conductor 31 intervening between the plug and the binding post 33 should be long enough so that after being thrown clear the casing 11, in order to avoid arestablishment of electrical contact; or else the peripheral parts of the head 29 and any e1;- posed parts of the post 28 should be made of or covered with insulating materlal.

In the form of plug illustrated in 3, the manufacture ofthe plug with precise accuracy is facilitated by providing a compressible Ainsulating washer 38, of felt or the like, between the posts head 29 and the body 20 ofthe plug. This permits of suitable contact being made between the disk 22 and the post 28, through the intervening Vthe hea-d 29 will hang below the bottom of leo ysolder 30, by a'quick process of manufac- I ture 'witliout the necessity of a highly precise accuracy' of thickness of solder plus length of post in order to make the head 29 tight against the plug 20.

- Another form of plug is'illustrated Fig. 4 in which the tubular plug 20 carries on .its inner face a cap 22 which is removable from that face of the plug except as it is held thereon by fusible solder at A spring 27 under compression, tends always case, when action occurs, the cap 22 is thrown into the burner chamber 15 and the spring 27 probably also will fall therein, leaving the circuit broken between the block 28 and the plug 20.

In both of-these cases, there is a sort of bridge, 22.0r 22 between a central part of the circuit and the outer part of the plug; and in one case the bridge is removed, by the fusing (Fig. 4) ,while in the other the connection to the bridge is removed (Fig. 3)

Although the apparatus is illustrated as it may be arranged to break an electrical circuit, 1t is clear that the spring might be arranged to work any other kind of device for shutting off the gas, andfeven for giving an alarm. v I

It is intended that the patent shall cover by suitable expressioninthe appended claims whatever features of atentable novelty exist in the invention disclosed.

I claim as myinvention u 1. A safety device for a gas burner having a mixing chamber, comprising the combination therewith of a gas supply valve and a device having a part which is fusible at a high temperature and which is setin position to be fused by the heat consequent u on' combustion occurring within4 the cham er, and not by heat of normal operationy of the i burner, and adapted on being fused to occasion the closing of said valve.

2. A safety device for a gas burner having a mixing chamber, comprisin the combination therewith of a gas supp y valve and a l device having a part which is fusible ata high temperature and which is set in position to be fused by the heat consequent upon combustion occuring within the chamber,

' and not by heat of normal operation of the.

burner, and an electrical circuit controlling the valve; said device being arranged to control the circuit lwhen the fusiblepart melts. 3'. A safety device for a gas burner having a mixing chamber, comprising the combination therewith of a gas supply valve adapted to be automatically closed and a device having a part which is fusible at a high temperature and which isset in position to be `fused by the heat consequent upon combustion occurring within the chamber, and not by heat of normal operation of the burner, and a normally closed electrical circuit controlling, v

the operation of the valve; the device being adapted to break the circuit on the fusing of said part.

.4. A safety device for a gas burner having a mixing chamber, comprising the combination therewith of a gas supply valve and a device having a part which is fusible at 'a' .hightemperature and which is set in position to be fusedby the heat consequent upon combustion occurring within the chamber, and not by heat of normal operation of the burner, and an electrical circuit controlling said valve and having parts held together b'y said fusible parts, adapted to move apart when said fusing occurs.

-5. A safety device for a gas burner having a mixing chamber, comprising the combination therewith of a gas supply valve, meansl for normally holding the valve open, "and a device having a part' which is fusible at a high temperature and which is. set in posi-4 tion to be fused by the heat consequent upon` combustion occurring within the chamber, and not by heat of normal operation of the burner; a spring released by the fusing; and means acted upon by the spring which, upon release of the spring, allows closing of the valve.

6. A safety devicevfor a gas burner having a mixing chamber, comprising the comsaid fusible part and adapted to be ejected therefrom upon the fusing of said part.

` 7 A safety ldevice for a gas burner having a mixing chamber, comprising the combination therewith of a gas supp y valve `and a device having` a part vwhich is fusible at a high temperature and which is set in posi-y tion to be fused by the heat consequent upon combustion occurring within the chamber,

and not by heat of normal operation of the burner, said device having one member arranged wit-hin another member, a spring also within the other member and compressed by the first member and tending to e separate thetw'o; the twov being heldtogether by said fusible part; and means whereby the separating of said two controls the closing of the valve.

8. A safety device for a -gas burner having a mixing chamber comprising the combination therewith of a gas supply valve normally held open and a device having la part which is fusible at a high temperature and which is set in position to be fused by the heat consequent. upon combustion occurring within the chamber, and not by heat ofgnormal operation of the burner, said device being a plug adapted tobe set in the wall of said chamber and connections adapted to permit the closing of said lvalve-when the fusin occurs.

9. safety device for a gasburner having a mixing chamber, comprising the combination'therewith of a gas su ply valve and a vdevice having a part whic is fusible at a high temperature and which is set in position to be fused by the heat consequent upon combustion occurring within the chamber, and not by heat of normal operation of thel burner; said device being a tubular plug having a' central anda peripheral part and connecting Vmeans forming successive parts of anormally closed electrical circuit; said circuit controlling the valve andl means whereby the fusing breaks the electrical circuit between said central and peripheral parts. 4

l0. A safety device for a gas burner having a valve and a mixing chamber, comprising the combinationtherewith of a thermal device actuated by a rise of temperature in the chamber beyond predetermined limits and adapted and connected to,v occasion the closing of the gas valve when so actuated.

1l. A safety device for a gas burner having a mixing chamber, and gas shutting-olf means, comprising the com ination therewith of a device set in the wall of the chamber and having a part stationary at normal operating temperatures of the burner and adapted to be moved on abnormal increase of tempera-ture in the region Where it is; and connections whereby such movement occasions operation of the gas shutting olf means.

Signed at Providence this thirteenth day of January, 1919. f i

IRA lw. KNIGHT. 

